You could be a USB antenna and interface card but as the previous user said you will be limited to the speed of your USB. If your Macbook Pro is just for normal use on a home network then you will not notice a huge difference. The type of band the Base station works on is a factor but other things such as how your network is being set up is another factor. Consider using the dual band feature on your current router if you have it available.

There are some USB stick devices for sale but Mac compatibility is questionable. If your Macbook Pro is limited to USB 2.0 then you will be limited to the speed of your USB connection. The total throughput of the USB inputs is shared between all devices using the USB ports. Actual speeds for USB 2.0 is about 280 Mbits or 35 Mbytes per second. Theoretical speed is 480 Mbits but this is the design limit, not the actual throughput.